Machine tool

ABSTRACT

A machine tool such as an NC lathe having a machine body is disclosed. The machine tool comprises a fixed bed, a machine body having a carriage with a tool post mounted thereon is provided on one side of the fixed bed nearer to an operator, and a headstock for loading a workpiece thereon is provided on another side of the fixed bed farther from the operator. The machine tool also includes a cover having a front wall and a side wall to cover at least a front face and a side wall of the machine body, respectively. The cover is provided so as to externally surround the machine tool, and wherein a portion of the side wall of the cover adjacent the tool post includes a door opening formed therein and a side door for opening and closing the door opening. Thus, the tool replacement work is facilitated and the overall workability of the machine tool can be improved.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a machine tool where the machinebody is surrounded by a cover. The machine body comprises a tool postdisposed on a fixed bed on one side thereof nearer to an operator, and aheadstock provided on the other side of the fixed bed farther from theoperator on which a workpiece is to be mounted thereon.

[0003] 2. Discussion of the Related Art

[0004] Conventionally a mass-production type machine tool (such as aNumerically Controlled lathe also called an NC lathe) has carriages witha tool post mounted on each carriage are provided on the left and rightsides of the front side (nearer side to the operator) of the fixed bed.A headstock is provided on the rear side (the side farther from theoperator) between the two tool posts. In each of the tool posts, aturret head with a plurality of tools mounted thereon is provided on atool post body so as to be rotationally indexable. In this arrangement,a workpiece mounted on the headstock is worked and shaped by moving thetool posts and the carriage relative to each other.

[0005] Also, in this machine tool, it has been conventional to have themachine body surrounded by a cover in order to prevent chips and coolantfrom scattering outside of the machine. In this arrangement, a wideoperational opening is formed in a front wall located on the operatorside of the cover so that the operational opening is opened and closedby a door.

[0006] With this conventional machine tool, since its structure has theheadstock disposed on the rear side of the left-and-right tool posts,the turret head is provided on the headstock side of the tool post body,i.e., on the rear side of the tool post body. As a result of thisstructure, replacing a tool set on the turret head requires the operatorto carry out the tool loading and unloading operation in a manner thatbrings his or her hands around from the operational opening formed inthe front wall to the rear side of the tool post body. In this machinetool, the tool post body interferes with the replacement work, resultingin a difficult replacement with poor workability.

SUMMARY OF THE INVENTION

[0007] The present invention has been accomplished in view of theseconventional devices.

[0008] An object of the present invention is to provide a machine toolthat allows the tool replacement work to be easily achieved and therebyallows the efficiency of the replacement work to be improved.

[0009] In order to achieve the above object and other objects of thepresent invention, in a first aspect of the invention, there is provideda machine tool comprising a fixed bed, a machine body having a carriagewith a tool post mounted thereon is provided on one side of the fixedbed nearer to an operator, and a headstock for loading a workpiecethereon is provided on another side of the fixed bed farther from theoperator. The machine tool also includes a cover having a front wall anda side wall to cover at least a front face and a side wall of themachine body, respectively. The cover is provided so as to externallysurround the machine tool, and wherein a portion of the side wall of thecover adjacent the tool post includes a door opening formed therein anda side door for opening and closing the door opening.

[0010] In a second aspect of the invention, in the machine tool asdescribed according to the first aspect of the invention, a protectordevice is provided for preventing chips from scattering between the sidewall of the cover and the tool post. A portion of the protector deviceadjacent the tool post includes an operational opening formed thereinand a shutter for opening and closing the operational opening.

[0011] With the machine tool according to the present invention, sincethe door opening is provided in the side wall of the cover adjacent thetool post, the tool replacement work can be done at a location near theturret head beside the machine body. This means that the tool post bodydoes not interfere with this work and allows the workability of toolreplacement task to be improved.

[0012] With the machine tool according to the second aspect of theinvention, since the protector device provided between the side wall ofthe cover and the tool post includes an operational opening and theshutter for opening and closing the operational opening, the toolreplacement work is facilitated by opening the shutter. Further, duringthe machining, the scattering of chips and coolant can be prevented byclosing the shutter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other objects and features of the present inventionwill be clearly understood from the following description with respectto the preferred embodiment thereof when considered in conjunction withthe accompanying drawings and diagrams, in which:

[0014]FIG. 1 is a perspective view of the machine body of an NC latheaccording to an embodiment of the invention, as viewed from an obliquefront side;

[0015]FIG. 2 is a perspective view of the machine body as viewed from anoblique rear side according to an embodiment of the invention;

[0016]FIG. 3 is a front view of a cover provided on the machine bodyaccording to an embodiment of the invention;

[0017]FIG. 4 is a plan view of the machine body according to anembodiment of the invention;

[0018]FIG. 5 is a front view of a headstock guide unit of the NC latheaccording to an embodiment of the invention;

[0019]FIG. 6 is a side view of a chip processing unit of the NC latheaccording to an embodiment of the invention;

[0020]FIG. 7 is a sectional view of a first clamp mechanism of themachine body according to an embodiment of the invention; and

[0021]FIG. 8 is a sectional view of a second clamp mechanism of themachine body according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinbelow, embodiments of the present invention are describedwith reference to the accompanying drawings.

[0023]FIGS. 1 through 8 are views for explaining a machine tool (NClathe) in accordance with the embodiments of the invention. The terms,front and rear, left and right, are referred to in this embodiment asthey are viewed from the operator side, that is, the near side means thefront, the farther side means the rear, the left side means the left,and the right side means to the right of the operator.

[0024] Referring to the figures, reference numeral 1 denotes a machinetool such as an NC lathe that is to be used, for example, to machinealuminum wheels. The NC lathe 1 is constructed so that its machine body2 is externally surrounded by a cover 3. In this machine body 2, asviewed from the operator, carriages 5 are provided on the left and rightsides of a front end portion (on one side nearer the operator) of afixed bed 4 so as to be movable in a Z-axis direction (back-and-forthdirection). Tool posts 6 are mounted on the individual carriages 5,respectively, so as to be movable in an X-axis direction (obliqueleft-and-right directions), and a headstock 7 is disposed on the rearside (on the side farther from the operator) of the fixed bed 4 betweenthe left-and-right carriages 5 so as to have its axis line directedalong the Z-axis direction and be movable in the Z-axis direction.

[0025] The fixed bed 4 is formed as a generally rectangular shapedparallelepiped by casting. Left-and-right sloped portions 4 a are formedin a front portion of this fixed bed 4 so as to form a V shape as viewedin a front view, while a flat portion 4 b stepped down from the slopedportions 4 a is formed in the rear portion.

[0026] A recessed portion 4 c for use in chip collection is formed as acut-out in the front portion of the fixed bed 4. This recessed portion 4c is surrounded by lower end portions 4 a′ of the sloped portions 4 a, afront end portion 4 b′ of the flat portion 4 b and a front end wall 4 dof the fixed bed 4. Also, a tunnel 4 e is formed within the flat portion4 b so as to communicate with the recessed portion 4 c, and a rear endof the tunnel 4 e is opens outwardly from a rear end wall 4 f of thefixed bed 4. The recessed portion 4 c and the tunnel 4 e comprise a chipcollecting passage through which chips occurring during the workpiecemachining operation are discharged rearwardly on one side of the fixedbed 4 that is opposite to the operator.

[0027] The carriages 5 are provided along the left-and-right slopedportions 4 a, and each of the carriages 5 is slidably supported by apair of upper-and-lower guide surfaces 8 formed in the sloped portion 4a. The carriage 5 is reciprocatingly driven in the Z-axis direction by adrive mechanism (not shown) such as a servomotor and ball screw.

[0028] Each of the tool posts 6 is generally structured so that a toolpost body 10 is fixed on a tool post base 9 slidably supported by thecarriage 5. Also, a turret head 11 with a plurality of tools mountedthereon is rotationally indexably provided on the rear face of the toolpost body 10. The tool post base 9 is reciprocatingly driven in theX-axis direction by a drive mechanism (not shown) such as a servomotorand ball screw.

[0029] The headstock 7, which is generally hemi-elliptically formed whenviewed in a front view, has a spindle 12 inserted therein and isrotatably supported by a plurality of bearings (not shown). A chuck 13for gripping a workpiece W is mounted on this spindle 12 and is driveninto rotation by a spindle drive motor (not shown).

[0030] As shown in FIG. 5, a fixed base 15 is fixedly attached on thetop of the flat portion 4 b of the fixed bed 4. Further, slide recessedportions 15 a, extending in the back-and-forth direction, are formed onleft-and-right side portions of the fixed base 15. A headstock base 16is provided on this fixed base 15 so as to be movable in the Z-axisdirection. This headstock base 16 has a rectangular plate shape thatextends in the back-and-forth direction and has the headstock 7 fixedlymounted thereon in a front portion thereof. Further, a rear portionthereof extends so as to protrude and overhang rearwardly from the rearend of the flat portion 4 b.

[0031] Protruding portions 16 a slidably engage with the slide recessedportions 15 a, respectively. Further, they are formed at bothleft-and-right end portions of the underside of the headstock base 16 sothat lower face and inner side face of each protruding portion 16 a arein surface contact with an upper face and an inner side face of theslide recessed portion 15 a. The headstock base 16 is reciprocatinglydriven by rotationally driving a ball screw 19 provided in the fixedbase 15 with a servomotor (not shown). The headstock 7 is movablebetween a workpiece machining position A where the workpiece W ismachined on the flat portion 4 b on the side farther from the operator,and a workpiece loading/unloading position B where the machinedworkpiece is replaced with the next workpiece above the recessed portion4 c on the side nearer the operator.

[0032] In this arrangement, when the headstock base 16 is at theworkpiece machining position A, the front portion of the headstock base16 where the headstock 7 is mounted is supported by the fixed base 15.When the headstock base 16 is at the workpiece loading/unloadingposition B, the rear portion of the headstock base 16 extending andoverhanging rearwardly from the front portion where the headstock 7 issupported by the fixed base 15.

[0033] First and second clamping mechanisms 20 and 21 for positioningand clamping the headstock base 16 to the fixed bed 4 are provided onthe fixed bed 4. The first clamping mechanisms 20 are provided on boththe left-and-right side portions of the headstock base 16, and thesecond clamping mechanism 21 is provided only on the left side portionof the headstock base 16, see FIG. 4.

[0034] As shown in FIG. 7, the first clamping mechanisms 20 aregenerally structured so that four pistons 23 are inserted within onehydraulic cylinder block 22 so as to be slidable up and down. Thehydraulic cylinder block 22 is fixed at the left-and-right end portionsof the top face of the fixed base 15 with a plurality of bolts 24.

[0035] A portion of the hydraulic cylinder block 22 including thepistons 23 is inserted and placed within a recessed portion 16 brecessed in a side wall of the headstock base 16 in a contactless mannerso that the pistons 23 are opposed to the protruding portion 16 a of theheadstock base 16. When oil pressure is supplied to an oil chamber 22 aof the hydraulic cylinder block 22, the pistons 23 go down, pressing andfixing the headstock base 16 to the fixed base 15. When the oil pressureis released, a spring 25 makes the pistons 23 go up so that the clampingforce is released.

[0036] As shown in FIG. 8, the second clamping mechanism 21 comprisesthree hydraulic cylinders 27 placed in parallel and fixedly bolted ontop of the flat portion 4 b of the fixed bed 4. A piston 28 is insertedwithin each hydraulic cylinder 27 so as to be horizontally slidable.Each of these pistons 28 is opposed to the left side face of theprotruding portion 16 a of the headstock base 16 through the fixed base15.

[0037] When oil pressure is supplied to an oil chamber 27 a of eachhydraulic cylinder 27, each piston 28 advances rightwardly to press andfix the headstock base 16 to the fixed base 15. When the oil pressure isreleased, the springs 29 make the piston 28 retreat so that the clampingforce is released.

[0038] The fixed bed 4 is equipped with a headstock guide unit forguiding and supporting the headstock base 16 between the workpiecemachining position A and the workpiece loading/unloading position B.This headstock guide unit has the following structure.

[0039] In the front face of the headstock base 16 a prismatic supportmember 33 extending widthwise is provided. Also, the support member 33is fixedly positioned by being coupled with the cutout portions 16 dformed by cutting out the headstock base 16 along its front lower edge.Guides 34 are fixed at both left-and-right end portions of the lowerface of the support member 33.

[0040] At the lower end portions 4 a′ of the left-and-right slopedportions 4 a of the fixed bed 4, planar portions 4 g are formed in astepped-down shape so as to extend in the back-and-forth direction alongthe lower end portions 4 a′. Rails 35 are fixedly bolted on the uppersurface of these left-and-right planar portions 4 g, and the guides 34are slidably engaged with these rails 35.

[0041] At the bottom of the fixed bed 4, as shown in FIG. 6, a chipprocessing unit is provided for collecting and discharging coolantsupplied to the cutting portion of the workpiece and chips generatedduring the machining. The structure of the chip processing unit isdescribed below.

[0042] A coolant tank 40 is provided within a chip collecting passagedefined by the recessed portion 4 c and the tunnel 4 e of the fixed bed4. This coolant tank 40 extends over the entire length of the recessedportion 4 c and the tunnel 4 e. The coolant tank 40 is further equippedwith a tank body 41 extending rearwardly from the rear end wall 4 f ofthe fixed bed 4 of the machine, and a discharge duct portion 42 risingup and extending obliquely and rearwardly from the rear end of the tankbody 41.

[0043] The tank body 41 is made up of left-and-right side walls 41 a anda bottom wall 41 b and is formed into an upward-opening box shape. Thedischarge duct portion 42 is formed into a cylindrical shape with itsrear end portion 42 a opening downwardly. Below the opening of this rearend portion 42 a, a chip collecting bucket 43 is provided.

[0044] An endless chip conveyor 44 is provided within the coolant tank40 so as to extend over the entire length thereof. The chip conveyor 44is rotationally driven by a drive motor (not shown). This chip conveyor44 is a strip conveyor made up by hinge-connecting a multiplicity ofthin strip plates to one another. The chip conveyor 44 serves to collectand convey chips that have dropped into the coolant tank 40 whileletting coolant and fine chips drop to the bottom wall portion 41 b.

[0045] At the bottom wall portion 41 b of the tank body 41, a slopedplate 45 is provided for cleaning away coolant and chips that havedropped through the chip conveyor 44 to a downstream end portion 41 d ofthe tank body 41. The sloped plate 45 is sloped from the front to therear side. Also, a resin film (not shown) is provided for smoothing thesliding of the chips. The film covers the upper surface of the slopedplate 45 and thereby the chips are prevented from sticking withoutincreasing the slope angle by virtue of the resin film.

[0046] A coolant collecting passage 46 communicates and connects to thedownstream end portion 41 d of the tank body 41, and a filter 47 forfiltrating the chips at an inlet of the collecting passage 46 isprovided. This collecting passage 46 communicates and connects a cleantank (not shown) provided, for example, in a separate chamber, so thatthe coolant is collected in the clean tank.

[0047] Chips and coolant generated during the machining operation dropinto the tank body 41 within the recessed portion 4 c and the chips areconveyed out of the machine by the chip conveyor 44 and collected in thecollecting bucket 43.

[0048] Meanwhile, the coolant and the chips that have passed through thechip conveyor 44 drop onto the sloped plate 45 and the coolant naturallyflows along this sloped plate 45. Then, this flow of coolant also causesthe chips to be cleaned away to the downstream end portion 41 d. Thechips that are cleaned-away in the coolant are filtered by the filter 47and are periodically collected. Further, the coolant from which thechips have been filtered away passes through the coolant collectingpassage 46, and is collected in the clean tank.

[0049] A cover 3, which is formed of an iron plate, covers thefront-and-rear faces, left-and-right side faces and top face of themachine body 2 as shown in FIG. 3. An operational door opening 50 isformed in a front wall 3 a of the cover 3 that covers the front face ofthe machine body 2. The door opening 50 has a lower edge set at aportion adjacent the headstock base 16, and an upper edge set at thefront edge of a ceiling wall 3 b.

[0050] The door opening 50 is provided with a pair of left-and-rightfront doors 51. Each front door 51 is supported so as to be slidablewidthwise. The front doors 51 each have a window 51 a with a transparentglass fitted thereto.

[0051] Side door openings 52 are formed in the left-and-right side walls3 c of the cover 3 that covers the left-and-right side faces of themachine body 2, respectively. Each of the door openings 52 is providedat a portion of the tool post 6 adjacent to the turret head 11 when thetool post 6 is in the standby position. The opening height and openingwidth of this door opening 52 are set to allow the operator to go in andout. A side door 53 for opening and closing the door opening 52 isprovided on the side wall 3 c, and the side door 53 is supported so asto be slidable in the back-and-forth directions.

[0052] A footstool 55 is provided at the door opening 52 so as tostretch over a range from an in-machine position beside the machine body2 to an out-of-machine position outwardly from the side door 53. Use ofthis footstool 55 gives the operator's hands access from the dooropening 52 to the tools of the turret head 11.

[0053] Around the left-and-right sloped portions 4 a of the fixed bed 4,a protector device 58 formed of an iron plate is provided. Thisprotector device 58 covers upwardly from the turret head 11 and in thevicinities of the carriages 5 of the sloped portions 4 a, therebypreventing chips from entering the sliding portions of the carriages 5.An operational opening 58 a is formed at a portion of the protectordevice 58 adjacent to the turret head 11. A sliding shutter 59 isprovided at the operational opening 58 a. Opening this shutter 59 allowsthe operator's hands to access the tools on the turret head 11.

[0054] For replacing the tools on the turret head 11, the operator itopens the side door 53, steps up on the footstool 55, enters into themachine through the door opening 52, and opens the shutter 59 of theprotector device 58.

[0055] The cover 3 is provided with a workpiece-machining-point displayunit for verifying whether or not the contents of previously inputtedmachining programs are operating correctly. Thisworkpiece-machining-point display unit is composed of a CCD camera 60 asan image pickup device provided inside the ceiling wall 3 b of the cover3, and a display (not shown) as an image display means provided on thefront wall 3 a of the cover 3. The CCD camera 60 is adjustably supportedin various angles by a support bracket 61 fixedly attached to theceiling wall 3 b. An image of the workpiece W on the headstock 7 placedat the workpiece machining position A is then displayed on the display.

[0056] With the workpiece-machining-point display unit of thisembodiment, since the CCD camera 60 is provided on the ceiling wall 3 bof the cover 3 so that a workpiece W set on the headstock 7 is imagedand displayed on the display by the CCD camera 60, a machining point ofthe workpiece W can be ascertained by the image at a place separate fromthe workpiece without the need for visually checking the machining pointdirectly from the machine outside through the window. This means thatprogram checks can be accomplished easily and securely.

[0057] Then, in the NC lathe 1 of this embodiment, while the carriage 5and the tool post 6 are moved in the Z- and X-axis directions,respectively, relative to each other, the workpiece W set on the spindle12 is subjected to a specified cutting process. In this case, theworkpiece W may be shaped either by the two tool posts 6 simultaneouslyor by each one tool post 6 alternately.

[0058] When the machining of the workpiece is completed, the carriage 5and the tool post 6 move to a specified standby position, where theheadstock base 16 is moved forward so that the headstock 7 is moved tothe workpiece loading/unloading position B. At this workpieceloading/unloading position B, the machined workpiece is unloaded and thenext workpiece is loaded. This workpiece replacement may also be doneautomatically by a robot.

[0059] As shown above, according to the NC lathe of this embodiment,since the headstock 7 is fixed to the headstock base 16 and since theheadstock base 16 movable between the workpiece machining position A andthe workpiece loading/unloading position B, the work of loading andunloading the workpiece W can be carried out in proximity to theoperator on the front side of the fixed bed 4. This allows the workpieceloading/unloading replacement to be improved.

[0060] In this embodiment, since the door openings 52 are provided inthe left-and-right side walls 3 c of the cover 3 so as to be adjacent tothe turret heads 11 of the tool posts 6, respectively, when the toolposts 6 are in their standby positions, and since the side doors 53 foropening and closing the openings 52 are provided, the work of replacingthe tools of the turret heads 11 can be carried out at a location inproximity to the turret heads 11 provided in the side portions of themachine body 2. This means that the tool replacement workability isimproved.

[0061] Also, since the operational opening 58 a is formed in theprotector device 58 provided on the in-machine side and since theshutter 59 for opening and closing the operational opening 58 a isprovided, the tool replacement work can be facilitated by opening theshutter 59. Further, the chips and coolant can be prevented fromscattering by keeping the shutter 59 closed during machining.

[0062] With the chip processing unit of this invention, since the chipconveyor 44 is provided within the coolant tank 40, the sloped plate 45is provided at the bottom portion, and since chips that have passedthrough the chip conveyor 44 are cleaned away to the downstream endportion 41 d by the coolant, the chips can be prevented from beingaccumulated at the tank bottom.

[0063] Also, the chips cleaned-away in the coolant are filtered by thefilter 47 and thus they can be periodically collected. This results in arelatively simple removal operation, and therefore the workingefficiency discharging these chips can be improved.

[0064] Furthermore, since the coolant filtered by the filter 47 iscollected to a separately placed clean tank, it becomes possible tosupply the coolant in the clean tank to the machining part of theworkpiece W, thus allowing the working efficiency for coolant collectionto be enhanced.

[0065] Also in this embodiment, since the recessed portion 4c for use inchip collection is provided in the front portion of the fixed bed 4,since the tunnel 4 e is provided in the flat portion 4 b so as to extendrearwardly adjacent to the recessed portion 4 c and be opened in therear end wall 4 f, and since the coolant tank 40 is provided within thechip-collecting recessed portion 4 c and the tunnel 4 e, it becomespossible to discharge the chips and coolant to a side opposite theoperator. This means that neither the coolant tank 40 nor the chipsinterfere with the workpiece loading/unloading work and this improvesthe workability of the design.

[0066] With the headstock guide unit, since the rails 35 extending inthe back-and-forth direction are fixedly bolted to the lower endportions 4 a′ of the left-and-right sloped portions 4 a of the fixed bed4, since the left-and-right guides 34 are fixed to the front end portionof the headstock base 16 via the support member 33, and since the guides34 are slidably engaged with the rails 35, support rigidity and supportstrength of the headstock 7 at the workpiece machining position A can beensured. Moreover the headstock 7 can be moved to the workpieceloading/unloading position B without any obstacles.

[0067] Also, even when the headstock base 16 overhangs during theworkpiece loading/unloading process, the headstock base 16 can besecurely supported by the slide of the guides 34 and the rails 35.

[0068] It is to be understood that although the present invention hasbeen described with regard to preferred embodiments thereof, variousother embodiments and variants may occur to those skilled in the art,which are within the scope and spirit of the invention, and such otherembodiments and variants are intended to be covered by the followingclaims.

[0069] The text of Japanese priority application no. 2000-281321 filedSep. 18, 2000 is hereby incorporated by reference.

What is claimed is:
 1. A machine tool comprising: a fixed bed; a machinebody having a carriage with a tool post mounted thereon is provided onone side of said fixed bed nearer to an operator; a headstock forloading a workpiece thereon is provided on another side of said fixedbed farther from the operator; and a cover having a front wall and aside wall to cover at least a front face and a side wall of said machinebody, respectively, wherein at a portion of said side wall of said coveradjacent said tool post includes a door opening formed therein and aside door for opening and closing the door opening.
 2. The machine toolaccording to claim 1, further comprising a protector device forpreventing chips from scattering is disposed between said side wall ofsaid cover and said tool post, and wherein a portion of said protectordevice adjacent said tool post includes an operational opening and ashutter for opening and closing the operational opening.
 3. The machinetool according to claim 1, wherein said cover is provided so as toexternally surround the machine tool.